Aspects of the present disclosure relate generally to wireless communication systems, and more particularly to Long Term Evolution (LTE) operations in the unlicensed channels.
Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks. As used herein, a “carrier” refers to a radio band centered on a defined frequency and used for wireless communications.
A wireless communication network may include a number of base stations that can support communication for a number of user equipments (UEs). A UE may communicate with a base station via the downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station.
A wireless communication network may support operation on multiple carriers. A carrier may refer to a range of frequencies used for communication and may be associated with certain characteristics. For example, a carrier may be associated with system information describing operation on the carrier. A carrier may also be referred to as a component carrier (CC), a frequency channel, a cell, etc.
An LTE UE device normally operates on the licensed frequency spectrum. The unlicensed frequency spectrum, however, may provide an inexpensive resource for wireless communications because no license is required to operate on the unlicensed frequency spectrum. In this context, there remains a need for mechanisms for exploiting carrier aggregation in the unlicensed bands.